Mars Environment

Although Mars has an atmosphere, it is unfriendly toward life as we know it on Earth. Mars is smaller than Earth in diameter; this results in a lower force of gravity - only about 1/3 of the gravity of Earth.. So if you weigh 60 kilos on Earth you will only tip the scales at about 20 kilos on Mars …  with no dieting. Partly as a result of the limited gravity on Mars much of the atmosphere of Mars has drifted away. With little atmosphere, and no ozone layer, there is less protection from the ultraviolet (UV) radiation of the sun, which is very harmful to life. This is similar to situations on Earth when living things are exposed to high concentrations of UV rays which produce "sunburn"; this is of greater concern in areas where there is a "hole" in the ozone layer, allowing increased levels of UV penetration to the surface.

Although the length of the Martian day (24 hours and 37 minutes) and the tilt of its axis (25 degrees) are similar to those on Earth (24 hours and 23.5 degrees, respectively), the orbit of that planet around the Sun takes almost twice as long as Earth. As a result, a Martian year is about twice as long as an Earth year and the seasons are each twice as long as those on Earth. The atmosphere is composed mainly of carbon dioxide (95.3%), nitrogen (2.7%), and argon (1.6%), with small amounts of other gases. Oxygen, which is so important to us on earth, makes up only 0.13% of the atmosphere at Mars and there is only one-fourth as much water vapor in the atmosphere.

Component Earth* Mars*
Carbon Dioxide 0.038% 95.3%
Nitrogen 78% 2.7%
Oxygen 21% 0.13%
Oxygen 0.93% 1.6%
Water Vapour 1.0% 0.25%
*figures may not add up to 100% due to rounding.

With little atmosphere, there is only a small buffer between the surface and space itself. This means that the temperature at the surface is very cold. The surface pressure averages about 1/100th that at the surface of the Earth. Surface temperatures range from -113°C at the winter pole to above 0°C at the equator on the dayside during summer.

At the Kennedy Space Center, the Tomatosphere seeds used in the experiment in an earlier year (2009) were subjected to a simulation of the Martian surface environment for a period of one week. The temperature in the simulator was approximately -50°C, with a 95% concentration of CO2 and an increased intensity of ultraviolet light, similar to that found on the surface of Mars. The pressure in the simulator was 0.6 kilopascals (kPa), compared to Earth which averages 101.32 kPa.